Impact of Urban Expansion on the Formation of Urban Heat Islands in Isfahan, Iran: A Satellite Base Analysis (1990-2019)

The expansion of urban areas leads to the development of urban heat islands (UHI), which can pose risks to human health and the environment. Understanding changes in vegetation, land use, and temperature variations in different regions is crucial for planning at both local and regional levels. This study aims to examine how urban sprawl affects the formation of heat islands in Isfahan, Iran. Using Landsat ETM satellite imagery from 1990 to 2019, the research analyzes land surface temperature (LST), normalized difference vegetation index (NDVI), urban growth, and land use changes. The study's empirical findings show a noticeable increase in the city's size along with a decrease in garden lands and peripheral pastures. Areas lacking vegetation cover are mainly found in urban areas, residential zones, and the higher southern and eastern parts of Isfahan. The highest NDVI indices are concentrated in the western and southeastern parts of Isfahan. Urban areas have more intense heat islands compared to other land use types, leading to differences in minimum, maximum, and average temperatures. This heat island effect worsens with the growth of residential areas and urban development. In contrast, irrigated agricultural lands and gardens have the lowest temperature intensity related to heat islands. Moreover, higher temperatures are mostly found in Isfahan's central core, surrounded by cooler zones on the outskirts. Agricultural areas, parks, and urban green spaces have moderate temperatures due to their proximity to urban areas, which helps moderate temperatures. Throughout the study period and historical data analysis, areas with average temperature levels have been dominant and are expected to continue in the future.